Funds are requested to update the dual laser EPICS V system of the CORE Cytometry facility (CCF), which was established in January 1982 as part of the Cancer Center Core Grant. The CCF is presently an intergral part of basic and clinical research activities of this cancer center involving more than twenty NIH- funded researchers with a total annual budget of approximately 3 millions dollars. Their research interests encompass all major areas of immunology, cell biology, biochemistry, genetics, cancer metastasis and drug pharmacology. A major instrument update is required to meet critical needs of NIH-supported researchers, including access to a dye laser, replacing old, slow 8-bit technology with faster 16-bit electronic components, and associated software support. Fluorescent probes which extend the emission range to the near infra-red, dye lasers with excitation range matching these new probes, and high speed computers with powerful data acquisition and storage capacity will permit in- depth analysis of the coordinated expression of several cellular properties such as oncogenes, hormone receptors, growth factors as well as DNA and RNA expression by single cells using 3-color analysis. Quantitation growth factors will be possible with the implementation of an autofluorescence correction device, which will significantly increase the sensitivity of FCM analysis.